CN115555586A - Rotatable telescopic stirring friction processing head and processing method - Google Patents

Abstract

The invention relates to a rotatable telescopic friction stir processing head and a processing method. The rotatable telescopic friction stir processing head mainly includes: a driving motor I, a stirring head, a stirring needle, a hydraulic telescopic system, a rotatable shaft shoulder, a transmission belt, Drive motor Ⅱ, landing gear to be processed. The rotating speed of the stirring needle and the rotatable shoulder can be adjusted by different motors. The double-rotating telescopic friction stir processing head of the present invention can carry out stirring processing on the aircraft landing gear manufactured by laser additive manufacturing, and can greatly improve the mechanics of the aircraft landing gear while realizing the adjustable structure of the surface and sub-surface of the additive manufacturing. Performance, reduce the surface roughness of the aircraft landing gear after adding materials, improve the surface quality, and reduce the processing procedures of aircraft landing gear additive manufacturing.

Description

A rotatable telescopic friction stir processing head and processing method

technical field

The invention belongs to the field of surface treatment, and relates to a rotatable telescopic friction stir processing head and a processing method, in particular to a rotatable telescopic friction stir processing head for landing gear of an aircraft, which can refine columnar crystals at the same time , to treat the surface of the added aircraft landing gear to improve its surface quality.

Background technique

Aircraft frequently suffer from "sprained feet" accidents. The main reason is that the load on the landing gear of the aircraft exceeds its ultimate carrying capacity during take-off or landing, which directly leads to the failure of key components of the aircraft landing gear. According to statistics, most of the key components are due to the strength and toughness of the key components. Mismatch. When the aircraft is in normal operation, the outer cylinder of the landing gear is displaced under the action of the piston to resist the energy brought by the impact. Stress concentration will inevitably occur at the interface and connection, and the force on the two wings of the landing gear In the case of small cases, in order to achieve the purpose of lightweight design, it needs to be optimized. The retractable landing gear requires the aircraft to be put down when taking off and landing. While adding the retractable mechanism, on the one hand, the weight of the landing gear system will increase significantly. On the other hand, the landing gear will inevitably appear structural cracks and fatigue fractures.

Laser additive manufacturing technology has opened up a new process technology approach for the design and manufacture of high-performance metal components, and can solve new challenges to materials, structures, processes, performance and applications in the development of aerospace and other fields. After years of development. Laser deposition manufacturing of metal components can reach or even exceed the mechanical properties of forgings, and its forming size is basically unlimited. It has become an important emerging means of rapid manufacturing of key aerospace components.

However, in terms of microstructure, laser directed energy deposition LDED: During the Laser directed energy deposition process, continuous growth of columnar grains is formed, resulting in low plasticity, toughness, damage tolerance and fatigue performance of A100 high-strength steel components; in terms of metallurgical defects, deposition Metallurgical defects occur inside the layer, between channels, and at the interface between layers, which greatly reduces the mechanical properties of the formed part. In addition, the structure of the aircraft landing gear is complex, and there are certain differences in the thickness and strength requirements of the components at different positions. Therefore, there is an urgent need for a flexible and efficient strengthening technology to strengthen the aircraft landing gear components of laser directed energy deposition. Friction stir processing technology, as a severe plastic deformation technology, can change the shape of the stirring head to control the depth and width of the processing zone according to the needs, and has high flexibility. In terms of microstructure, Friction Stir Processing FSP: Friction Stir Processing can destroy the growth of coarse columnar grains in the direction of material addition, refine the grains, and improve material properties. In terms of metallurgical defects, FSP can eliminate defects such as shrinkage porosity and shrinkage cavities in products, and improve the density of materials.

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the present invention proposes a rotatable telescopic friction stir processing head and a processing method. In view of the characteristics of different thicknesses at different processing positions of the aircraft landing gear, the stirring needles extend out different lengths and are inserted into the aircraft landing gear. The surface regulates the columnar crystals manufactured by additives, and at the same time rotates at different speeds through the shoulders, and simultaneously performs surface treatment on the additively manufactured components during the processing process to improve the surface quality and mechanical properties of the aircraft landing gear.

Technical solutions

A rotatable telescopic friction stir processing head, characterized by comprising a first drive motor I1, a stirring head 2, a stirring needle 3, a hydraulic expansion system 4, a rotatable shoulder 5, a transmission belt 6 and a second drive motor II7; The first driving motor I1 is connected to the stirring needle 3 in the stirring head 2 through the hydraulic telescopic system 4, the hydraulic telescopic system 4 and the stirring needle 3 are located in the rotatable shoulder 5, and the first driving motor I1, the hydraulic telescopic system 4, and the stirring head 2. The stirring needle 3 and the rotatable shoulder 5 are coaxial, and the first driving motor Ⅰ1 drives the stirring head 2 to move downward through the hydraulic telescopic system 4; The head 2 and the rotatable shoulder 5 are driven to rotate by the second drive motor II7, and the second drive motor II7 exerts a downward force on the stirring head 2 at the same time.

The roughness of the lower surface of the rotatable shoulder 5 is Ra50-100.

A method for processing aircraft landing gear using the rotatable telescopic friction stir processing head, characterized in that the steps are as follows:

Step 1: The rotatable shoulder 5 of the rotatable telescopic friction stir processing head is located directly above the surface of the landing gear of the aircraft to be processed, and the rotatable shoulder 5 is in contact with the surface of the aircraft landing gear to be processed;

Step 2: According to the different thicknesses of different processing positions of the aircraft landing gear, the stirring needle 3 is extended to the required length and inserted into the surface and sub-surface of the aircraft landing gear;

Start the first drive motor I1, so that the stirring needle 3 rotates at a high speed under the action of the first drive motor I1, and stir the columnar crystals after the material addition to achieve grain refinement on the surface and subsurface;

At the same time, start the second driving motor Ⅱ7, the transmission belt 6 drives the rotatable shoulder 5 to rotate, and at the same time provides the downward force F of the shoulder 5, so as to realize the material removal of the rough surface after the material is added, and realize the crystal grain on the stirring needle 3. At the same time of refinement, the surface roughness is lowered and the surface quality is improved.

The angular velocity ω ₂ of the rotatable shoulder 5 = kω ₁ {1/[(φ ₂ /φ ₁ ) ² -1]}, wherein: φ ₁ and φ ₂ are the diameters of the stirring head and the shaft shoulder respectively, and ω ₁ is the angular velocity of the stirring head, and k is the equilibrium constant.

其中：铝合金的F₀记为基准下压力，铝合金的抗拉强度记为σ₀，目标金属的抗拉强度记为σ。The downforce of the rotatable shoulder 5 determines the grain refinement of the surface and subsurface,

Among them: F ₀ of the aluminum alloy is recorded as the base downforce, the tensile strength of the aluminum alloy is recorded as σ ₀ , and the tensile strength of the target metal is recorded as σ.

The rotating speed of the stirring head is 200-300r/min.

The downward pressure of the rotatable shoulder 5 on the machined surface is 20-50N.

Said when the angular velocity is inversely proportional to its surface area, the optimal aftertreatment of the shoulder surface is obtained at this time.

Beneficial effect

The invention proposes a rotatable telescopic friction stir processing head and processing method. The rotatable telescopic friction stir processing head mainly includes: drive motor I, stirring head, stirring needle, hydraulic telescopic system, rotatable shaft shoulder, and transmission belt , drive motor Ⅱ, landing gear to be processed. The rotating speed of the stirring needle and the rotatable shoulder can be adjusted by different motors. The double-rotating telescopic friction stir processing head of the present invention can carry out stirring processing on the aircraft landing gear manufactured by laser additive manufacturing, and can greatly improve the mechanics of the aircraft landing gear while realizing the adjustable structure of the additive manufacturing surface and sub-surface Performance, reduce the surface roughness of the aircraft landing gear after adding materials, improve the surface quality, and reduce the processing procedures of aircraft landing gear additive manufacturing.

Beneficial effects of the present invention:

具体计算得出最优轴肩下压力F。可以大幅度降低表面粗糙度，提高表面质量。1 The shaft shoulder is driven by the drive motor Ⅱ to post-process the metal surface after the stirring needle treatment. According to different aircraft landing gear materials, different material shaft shoulders are selected for post-processing. Based on the downforce F ₀ of the aluminum alloy shaft shoulder, The tensile strength of the aluminum alloy is recorded as σ ₀ , and the tensile strength of the target metal is recorded as σ, according to

The optimal shoulder downforce F is obtained through specific calculation. It can greatly reduce surface roughness and improve surface quality.

2According to the aircraft landing gear of different materials, choose different materials and rotating speeds of stirring heads, and at the same time, set the angular velocity to be inversely proportional to its surface area. When the optimal post-processing shoulder surface is obtained at this time, assume that φ ₁ and φ ₂ are respectively is the diameter of the stirring head and the shaft shoulder, the angular velocity of the shaft shoulder 5 is ω ₂ , and the angular velocity of the stirring head is ω ₁ , according to ω ₂ =kω ₁ {1/[(φ ₂ /φ ₁ ) ² -1]}k is The balance constant calculates the optimal angular velocity of the post-treatment surface of the shoulder, combined with the adjustable pressure F of the shoulder, while ensuring the surface quality, the structure of the material to be processed can be adjusted, and the comprehensive mechanical properties of the material can be adjusted.

3. Use the agitator with adjustable extension length to process the aircraft landing gear after material addition. According to the thickness change of different positions of the landing gear, the length of the stirring needle can be adjusted to process the landing gear, improving the processing efficiency and landing gear processing. Surface dimensional accuracy.

Description of drawings

Fig. 1 is a sectional view of the processing head of the present invention

Fig. 2 is the lower surface of the shoulder of the processing head of the present invention

Fig. 3 is the connection relationship between the second driving motor II and the stirring head in the present invention

In the figure: 1-first driving motor I, 2-stirring head, 3-stirring needle, 4-hydraulic telescopic system, 5-rotatable shaft shoulder, 6-transmission belt, 7-second driving motor II.

detailed description

Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

计算得出其中铝合金的F₀记为基准下压力，铝合金的抗拉强度记为σ₀，目标金属的抗拉强度记为σ。This embodiment provides a double-rotating telescopic friction stir processing head for aircraft landing gear, which is characterized in that it mainly includes: a driving motor I1, a stirring head 2, a stirring needle 3, a hydraulic telescopic system 4, and a rotatable shoulder 5 , Drive belt 6, drive motor Ⅱ7. The hydraulic telescopic system 4 is connected to the stirring needle 3; the driving motor I1, the stirring head 2, the stirring needle 3, and the rotatable shoulder 5 are coaxial with each other and are located directly above the surface of the landing gear to be processed; the rotatable shoulder 5 and The driving motor II7 is connected through the transmission belt 6, and the stirring head 2 and the rotatable shoulder 5 rotate under the driving of the driving motor I1 and the driving motor II7 respectively. It is characterized in that: the extension length of the stirring needle 3 is adjusted by the hydraulic telescopic system 4, the purpose of which is to insert different lengths of the stirring needle 3 into the surface and subsurface of the aircraft landing gear according to the different thicknesses of different processing positions of the aircraft landing gear, and the stirring needle 3 Under the action of the driving motor I1, it rotates at high speed to stir the columnar crystals after material addition to achieve grain refinement on the surface and subsurface. At the same time, the shoulder 5 is in contact with the surface to be processed of the landing gear of the aircraft, connected with the transmission belt 6, and rotates under the action of the drive motor Ⅱ7, so as to realize the material removal of the rough surface after material addition, and achieve grain refinement at the stirring needle 3 At the same time, the surface roughness is lowered and the surface quality is improved. It is characterized in that the angular velocity ω ₂ of the shoulder 5 can be calculated according to the angular velocity ω ₁ of the stirring head, ω ₂ =kω ₁ {1/[(φ ₂ /φ ₁ ) ² -1]}φ ₁ , φ ₂ is the diameter of the stirring head and the shaft shoulder respectively, k is the equilibrium constant, and when the angular velocity is inversely proportional to its surface area, the optimal post-processing shoulder surface is obtained at this time. Among them, the downward force F of the shoulder 5 is changed under the action of the driving motor II7, so that the grain refinement of the surface and the subsurface can be better realized according to different surface materials, which can be determined by

It is calculated that the F ₀ of the aluminum alloy is recorded as the base downforce, the tensile strength of the aluminum alloy is recorded as σ ₀ , and the tensile strength of the target metal is recorded as σ.

The depth of the columnar grain refinement layer of the aircraft landing gear is determined by the insertion depth of the stirring needle 3, the depth range is 3-6mm, and the downforce is 40-80N.

The parameters of the friction stir processing are that the rotating speed of the stirring head is 200-300r/min, and the downward force of the shoulder 5 on the processing surface is 20-50N.

The hydraulic telescopic system 4 is connected with the stirring needle 3, and the length L of the deep part of the stirring needle is controlled through the expansion and contraction of the hydraulic system.

The rotatable shaft shoulder 5, the transmission belt 6 is connected with the drive motor II 7, and rotates under the drive of the drive motor 7.

The roughness of the lower surface of the shoulder is Ra50-100.

Processing Example 1

In this embodiment, the material of the additive engine undercarriage to be processed is A100 high-strength steel, which is processed and strengthened by using the stirring head designed in the present invention.

Before performing friction stir processing, the stirring pin is driven by the driving motor I to rotate and insert into the additive component. When the stirring pin is fully inserted into the additive component, the shoulder is in contact with the upper surface of the component, and at the same time, the driving motor 2 starts to work , the stirring head rotates in the opposite direction to the shaft shoulder.

During the stirring process, under the control of the hydraulic control system, the length of the stirring needle is changed according to the thickness change of the landing gear of the aircraft, and the depth of the stirring needle insertion ranges from 3 to 6 mm.

The technical parameters selected for friction stir processing are: the limit range of the insertion depth of the stirring needle is 3-6mm. The rotation speed of the stirring head is 250r/min, the downward pressure of the shaft shoulder on the processed surface is 40N, the rotation speed of the shaft shoulder is 150r/min, and the roughness parameter of the lower surface of the shaft shoulder is Ra 7.

After the stirring needle is fully inserted into the component, the entire stirring processing head performs a feed movement driven by the processing spindle to complete the post-processing strengthening of the entire aircraft landing gear.

At the same time, surface roughness and tensile performance tests were carried out on the components processed by the stirring head of the present invention, and the obtained surface roughness and tensile strength results are shown in Table 1.

Processing Example 2

In this embodiment, the material of the additive engine undercarriage to be processed is A100 high-strength steel, and a traditional stirring head is used to process and strengthen it.

Before performing friction stir processing, the stirring needle was driven by the drive motor I to rotate and inserted into the additive component. The depth range of the stirring needle was 4 mm.

The technical parameters selected for friction stir processing are: the insertion depth of the stirring needle is 4mm. The rotation speed of the stirring head is 250r/min, and the downward pressure of the shoulder on the machined surface is 40N.

After the stirring needle is fully inserted into the component, the entire stirring processing head performs a feed movement driven by the processing spindle to complete the post-processing strengthening of the entire aircraft landing gear.

At the same time, the surface roughness and tensile properties of the components processed by the traditional mixing head were tested. The obtained surface roughness and tensile strength results are shown in Table 1.

Table 1

Aiming at the deficiencies in the prior art, the present invention provides a double-rotating telescopic friction stir processing head for aircraft landing gear, which effectively solves the problem of additive manufacturing of aircraft through the coordinated operation of the stirring needle of the friction stir head and the rotation of the shaft shoulder. The difficult problem of columnar crystals in the landing gear is difficult to control, which effectively improves the surface quality of the components after friction stir processing, and realizes high-performance and high-efficiency machining of aircraft landing gear.

Claims (8)

1. A rotatable telescopic friction stir processing head is characterized by comprising a first driving motor I (1), a stirring head (2), a stirring pin (3), a hydraulic telescopic system (4), a rotatable shaft shoulder (5), a transmission belt (6) and a second driving motor II (7); the first driving motor I (1) is connected with a stirring needle (3) in the stirring head (2) through a hydraulic telescopic system (4), the hydraulic telescopic system (4) and the stirring needle (3) are located in a rotatable shaft shoulder (5), the first driving motor I (1), the hydraulic telescopic system (4) and the stirring head (2) are coaxial, and the first driving motor I (1) drives the stirring head (2) to move downwards through the hydraulic telescopic system (4); the rotatable shaft shoulder (5) is connected with the second driving motor II (7) through a transmission belt (6), the stirring head (2) and the rotatable shaft shoulder (5) rotate under the driving of the second driving motor II (7), and meanwhile the second driving motor II (7) exerts downward pressure on the stirring head (2).

2. The rotatable telescopic friction stir processing head of claim 1 wherein: the roughness of the lower surface of the rotatable shaft shoulder (5) is Ra50-100.

3. A method of machining aircraft landing gear using a rotatable telescopic friction stir machining head as claimed in claim 1 or claim 2 characterised by the steps of:

step 1: a rotatable shaft shoulder (5) of the rotatable telescopic friction stir processing head is positioned right above the surface of the undercarriage to be processed, and the rotatable shaft shoulder (5) is in contact with the surface of the undercarriage to be processed;

and 2, step: aiming at different thicknesses of different processing positions of the aircraft landing gear, the stirring pin (3) is inserted into the surface and the secondary surface of the aircraft landing gear by the required length;

starting a first driving motor I (1) to enable a stirring pin (3) to rotate at a high speed under the action of the first driving motor I (1) to stir the added columnar crystals, so that grain refinement of the surface and the subsurface is realized;

meanwhile, a second driving motor II (7) is started, the transmission belt (6) drives the rotatable shaft shoulder (5) to rotate, and meanwhile, the lower pressure F of the shaft shoulder (5) is provided, so that the material on the rough surface after material increase is removed, the surface roughness of the stirring pin is reduced while the grain refinement of the stirring pin (3) is realized, and the surface quality is improved.

4. The method of claim 3, wherein: the angular velocity omega of the rotatable shoulder (5) ₂ ＝kω ₁ {1/[(φ ₂ /φ ₁ ) ² -1]}, in which: phi is a unit of ₁ ，φ ₂ The diameters, omega, of the mixing head and the shoulder, respectively ₁ K is the equilibrium constant for the angular velocity of the stir head.

5. The method of claim 3, wherein: the downward pressure of the rotatable shoulder (5) determines the achievement of grain refinement of the surface and subsurface,

wherein: f of aluminum alloy ₀ The reference downforce and the tensile strength of the aluminum alloy were respectively expressed as σ ₀ The tensile strength of the target metal is denoted as σ.

6. The method of claim 3, wherein: the rotating speed of the stirring head is 200-300r/min.

7. The method of claim 3, wherein: the down pressure of the rotatable shaft shoulder (5) to the processing surface is 20-50N.

8. The method of claim 3, wherein: this results in an optimally post-treated shoulder surface when the angular velocity is inversely proportional to its surface area.

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